I stumbled on to the above web site at <http://www.fueleconomy.gov/> and have been tinkering with it and logging my mileage for a while. It is fun to poke around and compare different cars side by side.

One problem I've found with the web site is that the link in the lower left corner that says, "View MPG Estimates from Drivers Like You," only shows one 2004 Civic GX. But, if I log on and go to "Your Garage" I can see my '07 GX mpg and two other '07 GX mpg's that are shared.

I contacted the web master and they responded that there may be a problem with how Honda entered the model names in the mpg database over the years. The web master said they'll see if they can fix the hiccup so all years of shared data are listed under the link "View MPG Estimates from Drivers Like You."